The ornamental design for a shoulder of a tire, as shown and described.
The FIGURE is a perspective view of a shoulder of a tire showing my new
design, it being understood that the shoulder pattern is repeated
uniformly throughout the circumference of the tire as shown schematically
by solid lines, and the inner peripheral boundary of the shoulder is
defined by the stipple shading. The portions of the tire shown in broken
lines are for illustrative purposes only and form no part of the claimed
design.